1. Field of the Disclosure
This specification relates to a liquid crystal display (LCD) device, and particularly, to an LCD device and a fabricating method thereof.
2. Background of the Disclosure
In general, liquid crystal display (LCD) devices utilize properties of liquid crystals, such as optical anisotropy and polarity. Since the liquid crystal molecules have a long thin structure and an alignment orientation, alignment of the liquid crystal molecules can be controlled by artificial application of an electric field to the liquid crystals.
Accordingly, when the alignment orientation of the liquid crystal molecules is randomly adjusted, light is refracted toward the alignment orientation of the liquid crystal molecules due to the optical anisotropy, thereby displaying image information.
Currently, active matrix liquid crystal display (AM-LCD) devices, which have thin film transistors and pixel electrodes arranged in a matrix configuration, are being developed to have high resolution and an ability to display moving images.
The LCD device includes a color filter substrate (i.e., upper substrate) having common electrodes, an array substrate (i.e., lower substrate) having pixel electrodes, and a liquid crystal interposed between the upper and lower substrates. The common electrode and the pixel electrodes of the LCD device drive the liquid crystal molecules by an electric field formed in an up-and-down direction. Accordingly, the LCD device has high transmittance and large aperture ratio. But the LCD device has a low viewing angle characteristic due to the liquid crystal molecules being driven by the vertically formed electric field.
Therefore, to overcome the drawback, a new technology such as a liquid crystal driving method by fringe field switching (FFS) has been proposed. The liquid crystal driving method using the FFS exhibits a high viewing angle characteristic.
Hereinafter, the related art FFS mode LCD device having the advantage will be described with reference to FIG. 1.
FIG. 1 is a schematic planar view of an FFS mode LCD device according to the related art.
The FFS mode LCD device according to the related art, as shown in FIG. 1, includes a lower substrate 11 and an upper substrate 41 bonded to each other and having a display region AA and a non-display region NA defined thereon, respectively, and a liquid crystal layer 61 interposed between the lower substrate 11 and the upper substrate 41.
Here, the lower substrate 11 includes a plurality of gate lines (not shown) extending in one direction and spaced from one another in parallel, a gate electrode 13 perpendicularly extending from each gate line (not shown), a plurality of data lines (not shown) intersecting with the gate lines (not shown) to define pixel regions on intersections, respectively, and a thin film transistor (TFT) “T” disposed on each intersection between the gate line and the data line and having the gate electrode 13, an active layer 17 and source and drain electrodes 21 and 23. Here, although not shown, a gate pad (not shown) and a data pad (not shown) extend from one end of the gate line and one end of the data line, respectively. The gate pad and the data pad are connected to a gate pad connection line (not shown) and a data pad connection line (not shown).
Also, the lower substrate 11 further includes a pixel electrode 27 having a large area and electrically connected to the TFT T. An organic planarization layer 29 is formed on the lower substrate 11 having the pixel electrode 27. Here, the pixel electrode 27 is electrically connected to the drain electrode 23 forming the TFT T.
A plurality of common electrodes 31 corresponding to the pixel electrodes 27 are formed on the organic planarization layer 29. A lower alignment layer 33 is formed on the organic planarization layer 29 including the plurality of common electrodes 31.
Meanwhile, a black matrix 43 is formed between adjacent pixel regions (not shown) including the non-display region NA of the upper substrate 41, and a color filter layer 45 is formed on each pixel region (not shown).
An upper alignment layer 47 is formed on an entire surface of the upper substrate 41 including the color filter layer 45.
A seal pattern 51 is formed on outer edges of the non-display region NA to bond the lower substrate 11 and the upper substrate 41 to each other.
With the configuration, when a data signal is applied to the pixel electrode 27 via the TFT T, a fringe field is formed between the common electrodes 31 with a common voltage supplied thereto and the pixel electrodes 27 such that the liquid crystal molecules aligned in a horizontal direction between the lower substrate 11 and the upper substrate 41 are rotated by dielectric anisotropy. Also, a rotation level of the liquid crystal molecules decides transmittance of light transmitted through the pixel regions, thereby realizing gradation.
FIG. 2 is a schematic view showing a state that the seal pattern is spread in outer and inner directions of the non-display region upon bonding the upper and lower substrates of the related art LCD device.
In the related art FFS mode LCD device, as shown in FIG. 2, the seal pattern 51 is interposed between the lower substrate 11 and the upper substrate 41 to bond the upper and lower substrates 11 and 41 to each other. The seal pattern 51 is spread out in an outer direction of the non-display region NA by a first width W1 and in an inner direction of the non-display region NA by a second width W2.
Accordingly, taking into account a spreading tolerance (difference) of the width of the seal pattern and a spreading tolerance of the alignment layer, the related art LCD device has to ensure a distance from the seal pattern 51 to an end of the substrate by a predetermined distance, for example, over 0.2 mm. This is to prevent a defect of non-separation of a cell upon cell scribing due to the spreading of the seal pattern 51.
Also, in the related art, as the seal pattern 51 is spread out in the related art, the lower alignment layer 33 and the upper alignment layer 47 are also spread out of their areas to overlap the seal pattern 51. This causes a problem of lowering a bonding force.
As described above, it is difficult in the related art FFS LCD device to control the spreading of the seal pattern formed on the non-display region NA and the spreading of the alignment layer.
Also, it is likely to cause a defect that a cell is not separated during a cell scribing process when a margin is low due to the spreading of the seal pattern.
In addition, in the related art, due to the spreading of the seal pattern, the lower alignment layer and the upper alignment layer are also spread out of their areas to overlap the seal pattern 51, which causes a problem of lowering a bonding force.